1 /*
2 * id Quake II CIN Video Decoder
3 * Copyright (C) 2003 The FFmpeg project
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * id Quake II Cin Video Decoder by Dr. Tim Ferguson
25 * For more information about the id CIN format, visit:
26 * http://www.csse.monash.edu.au/~timf/
27 *
28 * This video decoder outputs PAL8 colorspace data. Interacting with this
29 * decoder is a little involved. During initialization, the demuxer must
30 * transmit the 65536-byte Huffman table(s) to the decoder via extradata.
31 * Then, whenever a palette change is encountered while demuxing the file,
32 * the demuxer must use the same extradata space to transmit an
33 * AVPaletteControl structure.
34 *
35 * id CIN video is purely Huffman-coded, intraframe-only codec. It achieves
36 * a little more compression by exploiting the fact that adjacent pixels
37 * tend to be similar.
38 *
39 * Note that this decoder could use libavcodec's optimized VLC facilities
40 * rather than naive, tree-based Huffman decoding. However, there are 256
41 * Huffman tables. Plus, the VLC bit coding order is right -> left instead
42 * or left -> right, so all of the bits would have to be reversed. Further,
43 * the original Quake II implementation likely used a similar naive
44 * decoding algorithm and it worked fine on much lower spec machines.
45 */
46
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50
55
56 #define HUFFMAN_TABLE_SIZE 64 * 1024
57 #define HUF_TOKENS 256
58 #define PALETTE_COUNT 256
59
65
67
69
70 const unsigned char *
buf;
72
75
78
79 /**
80 * Find the lowest probability node in a Huffman table, and mark it as
81 * being assigned to a higher probability.
82 * @return the node index of the lowest unused node, or -1 if all nodes
83 * are used.
84 */
87 int best, best_node;
88
89 best = 99999999;
90 best_node = -1;
91 for(
i = 0;
i < num_hnodes;
i++) {
93 continue;
95 continue;
96 if(hnodes[
i].count < best) {
99 }
100 }
101
102 if(best_node == -1)
103 return -1;
104 hnodes[best_node].
used = 1;
105 return best_node;
106 }
107
108 /*
109 * Build the Huffman tree using the generated/loaded probabilities histogram.
110 *
111 * On completion:
112 * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree.
113 * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree.
114 * num_huff_nodes[prev] - contains the index to the root node of the tree.
115 * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node.
116 */
118 hnode *node, *hnodes;
120
122 hnodes =
s->huff_nodes[prev];
125
126 while (1) {
127 node = &hnodes[num_hnodes]; /* next free node */
128
129 /* pick two lowest counts */
132 break; /* reached the root node */
133
136 break; /* reached the root node */
137
138 /* combine nodes probability for new node */
141 num_hnodes++;
142 }
143
144 s->num_huff_nodes[prev] = num_hnodes - 1;
145 }
146
148 {
150 int i, j, histogram_index = 0;
151 unsigned char *histograms;
152
155
156 /* make sure the Huffman tables make it */
159 return -1;
160 }
161
162 /* build the 256 Huffman decode trees */
163 histograms = (
unsigned char *)
s->avctx->extradata;
164 for (
i = 0;
i < 256;
i++) {
166 s->huff_nodes[
i][j].count = histograms[histogram_index++];
168 }
169
170 return 0;
171 }
172
174 {
176 long x, y;
177 int prev;
178 unsigned char v = 0;
179 int bit_pos, node_num, dat_pos;
180
181 prev = bit_pos = dat_pos = 0;
182 for (y = 0; y < (
frame->linesize[0] *
s->avctx->height);
183 y +=
frame->linesize[0]) {
184 for (x = y; x < y +
s->avctx->width; x++) {
185 node_num =
s->num_huff_nodes[prev];
186 hnodes =
s->huff_nodes[prev];
187
189 if(!bit_pos) {
190 if(dat_pos >=
s->size) {
192 return -1;
193 }
194 bit_pos = 8;
195 v =
s->buf[dat_pos++];
196 }
197
198 node_num = hnodes[node_num].
children[v & 0x01];
199 v = v >> 1;
200 bit_pos--;
201 }
202
203 frame->data[0][x] = node_num;
204 prev = node_num;
205 }
206 }
207
208 return 0;
209 }
210
212 void *
data,
int *got_frame,
214 {
215 const uint8_t *buf = avpkt->
data;
216 int buf_size = avpkt->
size;
220
223
226
229
231 /* make the palette available on the way out */
233
234 *got_frame = 1;
235
236 /* report that the buffer was completely consumed */
237 return buf_size;
238 }
239
241 { "max_pixels", "320*240" },
243 };
244
246 .
name =
"idcinvideo",
256 };